Existing sonic nozzles are utilized in industry as flow meter devices. Flow rates are calculated using fluid dynamic and thermodynamic relationships to calculate flow rate. However, there are inherent uncertainties associated with calculating flow rates in this manner.
In addition, existing nozzle banks utilize conventional de Laval nozzles, which have a smooth throat. A differential pressure is applied to the nozzle bank at sufficient pressure to induce sonic flow rate. There is a sensitivity of the mass flow rate through the nozzles due to changes in pressure across the bank. This sensitivity is due to the transfer of mass flow through the nozzle bank via a sub-sonic fluid flow boundary layer in each nozzle. This boundary layer effect adversely affects measurement accuracy. In contrast, to nozzles having a smooth throat, there are also known nozzles having abrupt changes in cross section.